the penalty is calculated on Form 2210, by default based on your safe harbor for the year, less withholding, divided by 4 against each quarterly due date, as you're expecting I think. To explain why you're seeing a penalty calculated as though that entire amount is due since Q1 you'd need to provide more details.
If you are on desktop you can bring up Form 2210 in Forms mode - it doesn't display by default but do Open Form and type in 2210. Not sure for TT Online equivalent but I assume it's shown in the PDF with all forms and worksheets.
the safe harbor will be the smaller of 90% of your 2025 tax, or 100% of your 2024 tax (110% if 2024 AGI > 150k or 75k if filing MFS) - see lines 1-9 on Form 2210.
if your quarterly distributions and other income were even throughout the year and you didn't pay withholding or ES then the Annualized Income method probably won't help (and note also for this method the quarters are uneven, ending 3/31, 5/31, 8/31, 12/31), but if your income is back-loaded towards later quarters you may be able to reduce the penalty (once you're comfortable with your original question about that default calculation to begin with). You can work thru this under Other Tax Situations / Underpayment Penalty section.
